def parse_bracket_expression(self):
token = self.pop_token() # remove left bracket
node = ASTNode(n_type=ASTNodeType.ARRAY_LIST_EXP,
n_line=token.get_line())
while True:
while self.get_token_type() == TokenType.EO_STMT:
token = self.pop_token() # EO_STMT
if str(token) == "," and node.children and node.children[
-1].get_text() == ',':
raise InvalidExpressionError3(token.row, token.col)
node.add_child(
ASTNode(n_type=ASTNodeType.EO_STMT,
n_text=token.get_text(),
n_line=token.get_line()))
if self.get_token_type() is None:
self.pop_token()
raise IncompleteStatementError(self.last_token.row,
self.last_token.col)
node.add_child(self.parse_logic_or_expression())
token = self.get_token()
if token.get_type() == TokenType.R_BRACKET:
break
self.pop_token() # remove right bracket
return node
def parse_identifier_list(self):
node = ASTNode(n_type=ASTNodeType.IDENT_LIST_EXP)
while self.get_token_type() == TokenType.IDENTIFIER:
token = self.pop_token()
node.add_child(
ASTNode(n_type=ASTNodeType.IDENTIFIER_EXP,
n_text=token.get_text(),
n_line=token.get_text()))
return node
def parse_identifier_expression(self):
token = self.pop_token()
root = ASTNode(n_type=ASTNodeType.IDENTIFIER_EXP,
n_text=token.get_text(),
n_line=token.get_line())
if self.get_token_type() == TokenType.L_PAREN:
self.pop_token() # remove left paren
node = self.parse_index_list()
self.pop_token() # remove right paren
root.add_child(node)
return root
def parse_statement_list(self, terminators=('None', )):
"""
when parse program, terminators use it default value, only if no token left will the parsing stop
when parse code blocks like selection, iteration, function, terminators will be some specified keywords
"""
node = ASTNode(n_type=ASTNodeType.STMT_LIST)
while str(self.get_token()) not in terminators:
if self.get_token() is None:
# indicates a invalid code block error, but raise outside the block
return None
if self.get_token_type() == TokenType.EO_STMT:
self.pop_token()
continue
node.add_child(self.parse_statement())
return node
def parse_iteration_statement(self):
if self.get_token().get_text() not in ('while', 'for'):
return None
node = ASTNode(n_type=ASTNodeType.ITR_STMT,
n_text=self.get_token().get_text(),
n_line=self.get_token().get_line())
start_token = self.pop_token()
clause = self.parse_iteration_clause(start_token.get_text())
if clause is None:
raise EndMissingError(start_token.row, start_token.col)
node.add_child(clause)
self.pop_token() # remove 'end'
return self.complete_statement(node)
def parse_level_7_expression(self):
"""
binary/trinary colon operator (left associate): :
"""
root = self.parse_level_6_expression()
while self.get_token_type() == TokenType.COLON:
token = self.pop_token() # ':'
node1 = self.parse_level_6_expression()
root = ASTNode(n_type=ASTNodeType.CLN_EXP,
n_text=token.get_text(),
n_line=token.get_line(),
children=[root, node1])
if self.get_token_type() == TokenType.COLON:
self.pop_token() # the second ':'
node2 = self.parse_level_6_expression()
root.add_child(node2)
return root
def parse_iteration_clause(self, clause):
node = ASTNode(n_type=ASTNodeType.ITR_CLS, n_text=clause)
expression = self.parse_logic_or_expression(
) if clause == 'while' else self.parse_assignment_expression()
if expression is None:
# exception raised outside
return None
node.add_child(expression)
statement_list = self.parse_statement_list(terminators=('end', ))
if statement_list is None:
# exception raised outside
return None
node.add_child(statement_list)
return node
def parse_selection_clause(self, clause):
node = ASTNode(n_type=ASTNodeType.SEL_ClS, n_text=clause)
if clause not in ('else', 'otherwise'):
expression = self.parse_logic_or_expression()
node.add_child(expression)
if clause != 'switch':
statement_list = self.parse_statement_list(
terminators=SEL_TERMINATOR_MAP[clause])
if statement_list is None:
# exception raised outside
return None
node.add_child(statement_list)
else:
# remove redundant EO_STMT tokens after switch before the first case
while self.get_token_type() == TokenType.EO_STMT:
self.pop_token()
return node
def parse_selection_statement(self):
if self.get_token().get_text() not in ("if", 'switch'):
return None
node = ASTNode(n_type=ASTNodeType.SEL_STMT,
n_text=self.get_token().get_text(),
n_line=self.get_token().get_line())
start_token = self.pop_token()
# firstly a if/switch
clause = self.parse_selection_clause(start_token.get_text())
if clause is None:
raise EndMissingError(start_token.row, start_token.col)
node.add_child(clause)
a, b = SEL_CLAUSES_MAP[start_token.get_text()]
# then unlimited elseif/case
while self.get_token().get_text() == a:
clause = self.parse_selection_clause(self.pop_token().get_text())
if clause is None:
raise EndMissingError(start_token.row, start_token.col)
node.add_child(clause)
# finally sometimes a else/otherwise
if self.get_token().get_text() == b:
clause = self.parse_selection_clause(self.pop_token().get_text())
if clause is None:
raise EndMissingError(start_token.row, start_token.col)
node.add_child(clause)
self.pop_token() # remove 'end'
return self.complete_statement(node)
def parse_index_list(self):
root = ASTNode(n_type=ASTNodeType.INDEX_LIST_EXP)
while True:
if self.get_token_type() == TokenType.COLON:
token = self.pop_token() # COLON
root.add_child(
ASTNode(n_type=ASTNodeType.CLN_EXP,
n_text=token.get_text(),
n_line=token.get_line()))
else:
child = self.parse_logic_or_expression()
root.add_child(child)
token = self.get_token()
if str(token) == ",":
# one argument finished, continue to parse another argument
self.pop_token()
continue
elif token.get_type() == TokenType.R_PAREN:
break
else:
raise InvalidExpressionError3(token.row, token.col)
return root